Nu-alkylhomogentisamide antistain agents for photographic materials



United States Patent N ALKYLHOMOGENTISAMIDE ANTISTAIN AGENTS FOR PHOTOGRAPHIC MATERIALS Richard L. Bent and Arnold Weissberger, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application July 27, 1953, Serial No. 370,598

4 Claims. (Cl. 95-6) This invention relates to color photography and particularly to the prevention of color staining or fog in photographic emulsions containing color couplers.

The incorporation of color-forming components or couplers in silver halide emulsion layers is well known. These couplers are compounds such as phenolic hydroxyl compounds or compounds with reactive methylene groups which are capable of reacting with the oxidation products of primary aromatic amino developing agents to produce indoaniline or azomethine dyes. The color couplers may be added directly to the emulsion layers as described in Fischer U. S. Patent 1,102,028, granted June 30, 1914, or they may be incorporated in a separate medium which is insoluble in the carrier for the sensitive silver halide as described in the Mannes and Godowsky U. S. Patent 2,304,940, granted December 15, 1942 and Jelley and Vittum U. S. Patent 2,322,027, granted June 15, 1943.

A difficulty frequently encountered in these processes is the formation of color fog or stain. This stain, which appears in the hightlight or white areas of processed pictures, may originate from several difierent causes. One cause may be that a small amount of developing agent is oxidized by the oxygen of the air, producing oxidized developer in small amounts which reacts with the colorforming couplers throughout the whole picture area. As a result, in the highlight areas of the picture in which no exposure of the silver halide has occurred, some dye stain is formed. An appreciable part of the dye stain may result from silver fog. It is Well known that color development produces a marked intensification effect, that is, that an amount of silver which is barely discernible will be associated with a fairly high dye density. Accordingly, a very small amount of silver fog in a colordeveloped image will be accompanied by an appreciable dye fog or stain. This small amount of silver fog is usually not readily controlled by the same procedures used to reduce higher amounts of silver fog to the level which is acceptable in black-and-white development.

It is, therefore, an object of the present invention to provide novel and useful antistain agents for incorporation in silver halide emulsions containing color couplers. A further object is to provide suitable antistain agents for use in solutions used to process such emulsions. A still further object is to provide antistain agents which may be incorporated in photographic developer solutions for developing emulsions containing color couplers and which do not reduce the stability of such solutions. Other objects will appear from the following description of our.

CHzC ONHR in which R is an alkyl group of from 6 to 18 carbon atoms, e. g., hexyl, octyl, decyl, dodecyl (lauryl), cetyl and octadecyl. Alkyl as used herein includes both unsubstituted and substituted alkyl groups.

Our invention is illustrated by the compound N-(ndodecyl) homogentisamide which has the formula CHaC ONHCuHu-n The compounds of our invention are usually incorporated in the emulsion and are non-diffusing in the emulsion although they may in certain cases be incorporated in the developing solution or in a pre-bath used prior to development. It is important that the antistain agent is present in the emulsion during color-forming development and it is essential that development with the color developing agent takes place in the presence of the antistain agent.

The following example illustrates the incorporation of the antistain agent in an emulsion layer.

One gram of the coupler N-[4-(benzoylacetamino) benzene sulfonyl]-N-('y-phenylpropyD-p-tolw idine and 0.1 gram of the antistain agent N-(n-dodecyl)- homogentisamide were dissolved at C. in 3 cc. of di-n-butylphthalate. This hot solution was poured with stirring into a solution containing 18 cc. of 10% gelatin, 2 cc. of water, and 2 cc. of 10% Alkanol B (sodium triisopropylnaphthalene sulfonate). The whole mixture was then passed several times through a colloid mill and the resulting fine dispersion was added, at 40 C. to 50 cc. of a melted positive-type emulsion. The mixture was then coated on a support in the normal manner and dried. The resulting coating gave a bright yellow dye image on color development and showed a marked reduction in stain over a similar material prepared without the antistain agent. On exposure of the coating to daylight for about 10 days, the dye image was found not to be appreciably affected by the presence of the antistain agent.

The compounds of our invention are prepared by treating homogentisic acid lactone with aliphatic amines. The lactone was prepared by the method described in Journal of Biological Chemistry 179, page 365 (1949). The compound N-(n-dodecyl)homogentisamide was prepared by reacting homogentisic acid lactone with dodecyl amine.

Our method is intended for use principally with emul- SlOIlS which produce a negative image upon direct development, that is, emulsions in which a negative image is formed upon development after exposure under a positive image or in which positive images are formed on development after exposure under a negative image. Our method may also be used with reversal color developers and with emulsions intended to be developed by reversal to form a colored image. Our agents are particularly useful with sensitive materials coated on paper supports, where it is' especially important to reduce the minimum or fog densities. This applies both to negative-developed paper and to reversal paper and transparency materials.

It will be understood that the examples and modifications disclosed herein are by way of example only and that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

1. In a process of color photography the method of preventing color stain in a photographic silver halide emulsion containing non-difiusing color coupler capable of reacting with the oxidation products of primary aromatic amino developing agents to produce indoaniline or azomethine dyes, which comprises exposing said emulsion and developing it with a primary aromatic amino developing agent in the presence of a compound having the formula CHaC ONHR where R is an alkyl group of from 6 to 18 carbon atoms. 2. A color-forming photographic silver halide emulsion .containing non-diffusing color coupler capable of re CHzC ONHR where R is an alkyl group of from 6 to 18 carbon atoms.

3. A color-forming photographic silver halide emulsion containing non-difiusing color coupler capable of reacting with the oxidation products of primary aro" matic amino developing agents to produce indoaniline or azomethjne dyes, and containing N(n-dodecyl)-homogentisamide as an antistain agent.

4. A multilayer photographic element comprising a support having thereon at least one silver halide emulsion layer containing a non-diffusing color coupler capable of reacting with the oxidation products of primary aromatic amino developing agents to produce indoaniline or ammethine dyes, and containing N-(n-dodecyl)-hom0- gentisamide as an antistain agent.

References Cited in the file of this patent UNITED STATES PATENTS 2,384,658 Vittum Sept. 11, 1945 2,403,721 Ielley et al July 9, 1946 

2. A COLOR-FORMING PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING NON-DIFFUSING COLOR COUPLER CAPABLE OF REACTING WITH THE OXIDATION PRODUCTS OF PRIMARY AROMATIC AMINO DEVELOPING AGENTS TO PRODUCT INDOANILINE OR AZOMETHINE DYES, AND CONTAINING AS AN ANTISTAIN AGENT THE COMPOUND HAVING THE FORMULA 